VLC support for dynamic resolution change in h264 stream

[gakkor]

Hi all,

I am trying to use VLC to play back a (an unorthodox...) h264 TS stream in which the resolution (width and height) changes in the middle. For example, it goes down from 352x288 to 176x144 for the same bitrate and frames/second. When the resolution changes, the stream starts as a new sequence, i.e. the media server actually stops the first stream and starts the a second one with the new resolution, but streams the output to the same address and port, so the VLC player is unaware of the change.

Now, different VLC versions react differently. VLC 0.8.6 shows a grayed-out, garbled image and even occasionally crashes. I get bunch of ffmpeg warnings of the type:

ffmpeg warning: top block unavailable for requested intra mode at 28 0
(h264 <at> 00B26890)
ffmpeg warning: error while decoding MB 28 0
(h264 <at> 00B26890)
ffmpeg debug: concealing 1350 DC, 1350 AC, 1350 MV errors

If I stop the VLC player and start listening again, the player syncs correctly to the new size stream.

If I try the same with vlc 0.9.4, it displays a blacked-out screen and the errors come from the vout module:

vout_directx error: overlay unuseable (might already be in use)
vout_directx error: overlay unuseable (might already be in use)

Again, if I stop and restart the player, it syncs to the new stream correctly.

Does anybody have a suggestion to overcome this problem? It may sound like a weird application, but consider a media server that streams multiple files of different resolution, and I want to watch them without stop/restarting my player.

Thanks in advance!
GA

[oxygens]

I have all the issues above, and other different ones past the first part with a given resolution:
- CoreAVC displays garbled video if video in a container;
- CoreAVC plays fine using a raw h264 stream, yet does not adjust the resolution;
- ffdshow crashes
Sorry for the lack of details for each of the above.

It would be nice if VLC could understant dynamic resolution, at least for h264.

The only player which plays a h264 with dynamic resolution is Flash (via Adoba Flash Player, or using the Flash platform), in a FLV container (I haven't tested with a MP4 container).

I am writing here because I am in search of means of transcoding (or possibly remuxing, although remuxing won't solve playability) of an FLV with dynamic resolution changes to anything, hopefully a MP4/h264.

Help!

[Lotesdelere]

h264 with dynamic resolution

Please, upload a short sample of such a file to either http://streams.videolan.org/upload/ or to Multiupload.com, so it will upload the file for you to several other hosts, and then post the link to the file here.

[oxygens]

Using FLVExtract from http://moitah.net/ I got a raw h264 stream and a raw AAC stream.

Then, using ffmpeg, i muxed those together into an MP4 and VLC played the video file (0.5 seconds blackout occurred when switching resolutions).
VLC played the file, but with a small bug: the second resolution didn't stretch normally, and it went outside the screen (as if each pixel from the first resolution had to match each pixel in the second resolution).

I have prepared samples (FLV which doesn't work in VLC, MP4 which does work, but does not scale resolution).
http://kakao.ro/public/VLCDynamicResolutionSamples/
In the samples, the first 2 seconds are 320x256, the next seconds are 720x576.

[Jean-Baptiste Kempf]

Is there a bug registered for that issue?

[oxygens]

I'm not sure wether it's a bug or a missing feature.

Looks like a feature to me, since most players/decoders (all that I've tested, except Adobe Flash/Adobe Media Player) fail at dynamic resolution switching one way or another.

Could be a bug since all is left to do for VLC, in the case of MP4/h264, is stretch correctly (I did not test other containers, other than FLV and MP4).
In the case of FLV container, it's surely a bug, a separate one than the one above.

[Jean-Baptiste Kempf]

Still, it should be in the bugtracker with the link to samples.

[oxygens]

Could you point me to the landing page of the bug tracker? I've found a lot of instructions about VLC bug reporting, yet I couldn't locate the actual bug tracker:) (shame on me)

[Jean-Baptiste Kempf]

trac.videolan.org/vlc/

[oxygens]

MP4/h264 stretching problem:
http://trac.videolan.org/vlc/ticket/5367

FLV/h264 plaing stops problem:
http://trac.videolan.org/vlc/ticket/5366

[Jean-Baptiste Kempf]

Nice.